diff --git a/requirements.txt b/requirements.txt
index 23dc58fde626c364d58edc0b6ac7d76f077412b7..faf34174fc2bb63d9c44706feb097f8f2b619dee 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,5 +2,4 @@ h5py>=2.9
 nibabel>=2.4
 numpy>=1
 scipy>=0.18
-six>=1
 dataclasses
diff --git a/setup.py b/setup.py
index 44e3412819be89bd961b25980231f2ade676d0ba..60c5d46c22b80ed27ad076a5e4ffe4c4b41c057e 100644
--- a/setup.py
+++ b/setup.py
@@ -8,8 +8,9 @@
 
 from __future__ import print_function
 
-import os.path as op
-import            shutil
+import os.path       as op
+import                  shutil
+import unittest.mock as mock
 
 from setuptools import setup
 from setuptools import find_namespace_packages
@@ -68,11 +69,6 @@ class doc(Command):
 
         import sphinx.cmd.build as sphinx_build
 
-        try:
-            import unittest.mock as mock
-        except:
-            import mock
-
         mockobj       = mock.MagicMock()
         mockobj.__version__ = '2.2.0'
         mockedModules = open(op.join(docdir, 'mock_modules.txt')).readlines()